The goal of this project is to deepen our understanding of the impact of early left focal lesions on linguistic information-processing. Using on- line experimental methods, this project examines the extent to which comprehension and production in real time are differentially impaired for children with different sites and types of early left focal lesions. The proposed studies investigate the effects of early focal lesions on (1) on- line processing during both comprehension and production, (2) processing differences across specific linguistic domains, and (3) processing profiles for individual subjects. Previous research on this topic has several limitations: (l) it has focused primarily upon production in contrast to comprehension, (2) it has made little use of experimental procedures, focusing instead on parental reports and spontaneous speech samples, (3) it has made no use of on-line methodology to study the processing of language in real time, and (4) it has failed to distinguish subjects fully according to both site and type of lesion. The present study focuses on early left focal lesions secondary to either cerebral infarct (CI) or periventricular hemorrhage (PVH) in 40 children. Magnetic resonance imaging (MRI) scans will be obtained on all subjects and analyzed using a standard procedure. The theoretical model used to guide the research is provided by the Competition Model -- a general model of linguistic information-processing, that has been used extensively in a variety of languages with both normal subjects and speakers with language impairments. Using the PsyScope experimental system, the current study measures real-time simultaneous processing and integration of verbal information across different linguistic domains. These tasks have been used extensively with both normals and adult aphasics. Recently, they have been piloted with normal children and children with language impairments. These on-line experimental techniques allow us to: (l) characterize the nature of performance deficits as they relate to site (anterior/posterior), and type of lesions (CI vs. PVH) for children with early focal brain lesions; (2) investigate the relationship between the comprehension and production deficits; (3) determine at what level the processing skills are impaired (e.g. lexical, sentence, or discourse) and; (4) determine the extent to which individual profiling techniques better characterize the nature of the deficits. Tasks being examined include base reaction time, signal detection, serial recall, auditory memory, rapid syllable production, picture naming, lexical decision, picture choice, constrained sentence production, error detection, cross-modal probe recognition, on-line sentence interpretation, constrained story production, and on-line story interpretation. Data gathered in these studies will be used to construct maximum likelihood models for individual subjects which then will be compared to control models in terms of theoretically defined mathematical "lesions" for particular parameters in the model.